Earthly Things: Snow insulates perennials, woody plants

By The Montana Standard Staff - 12/12/2008

If I recall, the Farmers' Almanac had predicted that this winter was going to be very cold and have a fair amount of snow.

So, where is the snow?

So far, the lack of snow has made for a less-than-stellar hunting season, a late start to the ski season, and the sleds are still in the garage.

The lack of snow has me a bit worried. Perennials and woody plants in our landscapes benefit from snow. Snow acts as an insulator for the roots of many woody plants and perennials. Although many of the above-ground parts of woody plants around the area can survive below zero temperatures, the roots are a different story.

Roots are more sensitive to cold and normally would not survive in our cold temperatures if they were not insulated by the soil that surrounds them. Without the soil as an insulator, roots would generally die back at a temperature of 15 degrees above zero. A blanket of snow helps to further insulate the roots from the cold temperatures.

If you have cold-sensitive plants or are trying perennials that push our USDA hardiness zone of 2 or 3, you may want to add some type of mulch such as straw to keep the roots from freezing. I recommend adding 3 to 4 inches of mulch around the base of the plants. Make sure if you are using straw that it is weed-free.

If it does snow again, try shoveling snow around the shrubs and on top of the perennials to help keep their roots insulated from the cold temperatures.

Toby Day is the Butte-Silver Bow Extension Agent specializing in horticulture and 4-H. He may be reached at the Butte-Silver Bow Extension office at 305 W. Mercury No. 302 in Butte, by phone at 723-0217, or by e-mail at tday@montana.edu.